Switchboard incandesoent lamp



Deg 18 1923.

H. T. BELLAMY SWITCHBOARD VINCANDESCENT LAME Filed June 23, 1919 M Wm Qa? Z M/ if J J Patented Den 1%,

TRISTBAM. BELLAIBTZ, Q1 OAK ELLINQES, ASSIiG-NOR TU W TERI?) CQIKPANY,INCOBPDRATED, U}? NEW YORK, 1Q. '31, A CQRZPGRATIGET 8F NEW"SWITCEIBOABD ZI l'CEANDEEWENT LAB/IE.

implication filed June 23,

Z all 107mm it may concern.

Be it known that 1, HARRY Tius'rRAM BELLAMY, a citizen of the UnitedStates, residing at Oak Park, in the county of Cook and State ofIllinois, have invented certain new and useful Improvements inSwitchboard Incandescent Lamps, of which the following is a full, clear,concise, and exact descri' tion.

W '1 is invention relates to incandescent lamps such as are used intelephone switchboard signalling, and more particularly to an improvedform and construction of globe for such lamps.

15 The object of the invention in general is to provide a globe whichmay be easily and economically produced and one which will greatlyimprove the end illumination of such signaling lamps.

In accordance with the general features of this invention there isprovided a molded or drawn lamp globe having a substantially flat endwall which is of uniform thickness throughout. Such a globe may beproduced 25 by the process and with the mechanism shown and described inthe Bellamy-Smith Patent No. 1,303,452, issued May 13, 1919, modified toprovide a fiat pad for producing a substantially flat end Wall in theglobe.

In the drawings illustrating this invention Fig. 1 is a view inelevation of a lamp globe blank embodying the features of thisinvention;

35 Fig. 2 is a longitudinal sectional view of a completed lamp made withthe globe of this invention, and

Fig. 3 is a view in elevation of the completed lam shown in section inFig. 2.

459 In the rawin 5 designates a hollow cylindrical glass lank which maybe produced in accordance with the invention described in theBellamy-Smith Patent 1,303,452, issued May 13, 1919, wherein a 455 flatpad employed instead of the concave pad disclosed. This cylindricalmember is provided at one end with an approximately flat end wall 6which is of substantially uniform thickness throughout. At its opposite1919. Serial. No. 306,170.

end the blank is provided with a flange or bead 7 which in themanufacture of the lamp proper is merged or fused into a glass tube 8through which the globe is evacuated and which supports supporting wiresor terminals 99, to the upper ends of which is e attached a filament 10.The lower ends of the supporting wires are brought out through the wallof the globe andsecured to terminals 1111 which are cemented to theglobe and have their lower ends 1212 secured to within an insulatingbase 13.

With this form of globe the light filament 10 may be located closelyadjacent the end wall 6 thereby directing the maximum number of lightrays through the Wall. Due-to on the approximately flat contour of theend Wall all or approximately all oi the light rays which a re directedthrough it from the filament '10 will be directed in an approximatelyperpendicular direction to illuminate a lamp cap which is located abovethe lamp in the construction of telephone switchboards to which thisinvention is particularly applicable. Moreover, since the end wall 6 isof uniform thickness there will 7 be practically no distortion ordeflection of the light rays from the filament 10. and the eliiciency othe lamp with respect to its illumination is thereby greatly increased.

1n the previous known methods of producing these lamp globes, namely, bytaking a glass tube and heating and working the end thereof to close it,it-has not been pos-" sible to approximate a flat end wall or a wallhaving a uniform thickness. These diflicul= ties, however, have beenovercome by the drawing and forming process of the Bellamy-Smith patentheretofore referred to, making it possible to produce the globes of thisinvention on a commercial scale.

What is claimed is:

A telephone switchboard incandescent lamp having a substantially flatend wall of uniform thickness.

In witness whereof, I hereunto subscribe 5

